The invention relates to a circular saw arrangement or assembly with a support for the workpiece to be cut and with a saw unit containing the powered saw blade which saw unit is carried by an elongate guide means located above said support the guiding portion of said guide means being at a constant distance from the support wherein the saw blade can be reciprocated in the longitudinal direction of the guide means and can be lowered from an elevated position.
With a known circular saw arrangement of this type (See published German Patent Application 37 37 814 and German Patent Application 39 23 470) the saw unit containing the saw blade is pivotable, but mounted non-movable in the longitudinal direction of the guide means at the front end of the elongate guide means which for example can comprise two parallel guide rods. The guide means is mounted movable in its longitudinal direction in a bearing arrangement which is securely connected with the table arrangement. The saw blade present in the saw unit can therefor be lowered from an elevated position about a pivot axis present in the area of the connection with the guide means, so that a chop-cut saw function results. In addition, the guide means with the saw unit mounted at its front end can be displaced in the longitudinal direction of the guide means relative to the bearing, so that a rip-saw function results. One advantage of this known arrangement is that moving the elongate guide means relative to the bearing arrangement always maintains the pivot axis for the saw unit at the same perpendicular distance from the support for the workpiece, so that the saw blade can be moved in a defined lowered position together with the guide means in its longitudinal direction thereof and thus a notch or groove of pre-given depth, constant over its total extent, can be produced in a workpiece.
Whereas the known circular saw arrangement, with a compact structure, unites a chop-cut saw and a rip-saw function, it has the considerable disadvantage that, in the starting position of the saw unit, i.e. when the saw unit is located at the smallest distance from the bearing arrangement for the elongate guide means, the elongate guide means extends far beyond said bearing arrangement on the rearward side of the bearing arrangement facing away from the saw unit. When using the known circular saw arrangement care must therefore be taken that sufficient free space remains behind the floor space for the guide means to move in its longitudinal direction. The greater the desired cut width of the circular saw arrangement is, the greater the size of this free space must be. Obviously, this considerably weakens an essential advantage of the combination of chop-cut saw function and rip-saw function in a circular saw arrangement, because this design requires considerable space when in operation.
A circular saw arrangement is also already known (See published European Patent No. 0 242 733) which combines the chop-cut saw function and rip-saw function and in which an elongate guide means in the shape of a guide rods is pivotable against spring force, but in its longitudinal direction is mounted non-movable to the table arrangement. The saw unit containing the saw blade is movable on this guide means in the longitudinal direction from a position near to the connection of the guide means and the table arrangement in the direction of the free end of the guide means, and the saw blade can be lowered from its elevated position by pivoting the guide means against spring force.
This known design has the advantage that during operation the guide means is not moved out over the side of the connection of the guide means and the table arrangement facing away from the saw unit, so that it is not necessary to have free space at the rear of the circular saw arrangement as is the case with the previously mentioned circular saw arrangement with its guide means movable in longitudinal direction. However, the difficulty with the known circular saw arrangement with guide means non-movable in its longitudinal direction is that it is not possible when carrying out a rip-saw cut to guide the saw blade at an exact, perpendicular distance from the support and thus produce a notch or groove of constant depth in a workpiece, because the saw unit is lowered by pivoting the guide means in the area of one of the ends thereof. To achieve a notch or groove of constant depth in a workpiece while the user moves the saw unit along the guide means, the guide means would therefore have to be continuously and accurately pivoted, which is not feasible.
Moreover, the known circular saw arrangement with guide means pivotable, yet non-movable in longitudinal direction has the disadvantage that the force to be applied to pivot the saw unit when moving the saw unit towards the free end of the guide means continuously increases. Because the guide means in its starting position is urged upwardly towards its free end by the action of the spring, the force to be applied by the user to overcome the spring force pressing the guide means with its pivoted-up position becomes greater the further the saw unit is moved towards the free end of the guide means, and thus, the saw unit must be held in an essentially defined lowered position relative to the support.
So-called radial arm saws are also known (U.S. Pat. No. 2 559 283) in which a saw unit carrying a powered circular saw blade can be moved over the support of a table arrangement along an elongate guide means which is non-movable in its longitudinal direction; the guide means running parallel to the support and the saw blade being thus guided through the workpiece with a constant penetration depth. However, in order to change the penetration depth of the saw blade with these radial arm saws, the user must operate the guide in the perpendicular direction, and set it to the desired penetration depth before the actual sawing operation to change the distance of the guide means from the support. This requires a very solid structure in order to, on the one hand, keep the guide means stable and, on the other hand, to permit its adjustment in the perpendicular, so that such a structure is practically suitable only for relatively large machines to be used professionally. Moreover, with such a machine, a chop-cut saw function is not possible, which, however, is desired in many applications to carry out separation tasks quickly.
It is the aim of the invention to provide for a circular saw arrangement with combined chop-cut saw function and rip-saw function, which, with a compact structure and occupying little space during use, permits notches or grooves of constant depth to be produced in a workpiece and in which the force to be applied to lower the saw blade is independent of the position of the saw unit.
To achieve this aim a circular saw arrangement of the initially mentioned type is designed so that the elongate guide means is mounted non-movable in its longitudinal direction with respect to the support and the saw unit is movable along the guide means.